1. Field of the Invention
The present invention relates to members with which an ink comes into contact (hereinafter referred to as xe2x80x9cink-contacting membersxe2x80x9d), such as ink-absorbing members, ink tanks and ink cartridges which are used in ink-jet recording apparatus.
2. Related Background Art
An ink-jet recording apparatus has a general construction that an ink tank for storing an ink therein, and an ink-jet recording head portion for ejecting the ink from the ink tank to conduct printing are connected to each other directly or through an ink-feeding member such as a tube. In such an ink-jet recording apparatus, resin materials, metallic materials, rubber materials and/or the like have heretofore been used for members always coming into contact with an ink. Of these materials, the resin materials have preferably been used from the viewpoints of cost and processability.
Examples of the resin materials include polyolefins, ABS, PS, PET, PVC, etc. Of these resin materials, the polyolefins are particularly preferably utilized from the viewpoints of the chemical resistance, the easiness to be recycled and the costs. Examples of the polyolefins include polyethylene, polypropylene and ethylene-propylene copolymers.
It has been known that additives are generally added to such a resin material, as needed, for the purpose of stabilizing its quality. In some cases, the resin materials may be oxidized by heat, light, oxygen or the like during their manufacturing process or processing process, or after the processing to cause decomposition or deterioration (autoxidation). Therefore, it is desirable to add an antioxidant to the resin materials taking the stability of quality into consideration.
Of autoxidation mechanisms of the resin materials, for example, the following mechanisms are well known.
An antioxidant is added for the purpose of preventing the autoxidizing action. It is also desirable to add a radical scavenger to the resin materials in order to scavenge radicals generated at the initial chain propagation step of the autoxidizing action. Examples of the radical scavenger include phenolic antioxidants and amine type antioxidants.
An ink-jet recording head portion of an ink-jet recording apparatus will now be described. An energy-generating member such as a piezoelectric element or electrothermal converter is used as a member for applying a pressure for ejecting an ink in the ink-jet recording head. A thermal ink-jet recording head in which an electrothermal converter is used as the energy-generating member will be described. In this head, an extremely small amount of ink adjacent to the electrothermal converter is rapidly heated by the electrothermal converter, whereby the ink is bubbled. The ink is ejected toward a recording medium such as paper from ink ejection orifices by a pressure generated by this bubbling, thereby conducting recording.
An example of the construction of this ink-jet recording head will be described by reference to FIG. 5.
An ink-jet recording head 51 has several to several tens of, and further several hundreds of ink ejection orifices 52 at its surface opposite to a recording medium such as paper (two orifices thereof being illustrated in FIG. 5). The ink-jet recording head 51 is also provided with ink flow paths 53 in respective communication with the ink ejection orifices 52, and energy-generating members for ejecting an ink, or thin film resistors 55 as electrothermal converters in this case are formed in correspondence with the respective ink flow paths 53 on a substrate 54 which makes up the ink-jet recording head 51.
Each of the thin film resistors 55 rapidly generates heat by electric pulses applied in response to drive data to bubble the ink adjacent to the thin film resistor 55. The ink is ejected from the ink ejection orifice 52 following the formation of bubbles by this bubbling. A common liquid chamber 56 commonly connected to the ink flow paths 53 is provided at the respective ink flow paths 53, and the ink stored in the liquid chamber is fed to the ink flow paths 53 in response to the ejecting operation in the respective ink flow paths 53.
Generally, ink-contacting members in an ink-jet recording apparatus are generally constructed by plural members such as an energy-generating member and an ink feed tube, and these members slightly differ in wettability with inks from each other, so that the flow of the ink passing through the ink-contacting member may become unstable. When the ink is ejected at a high speed in particular, therefore, the supply of the ink to the ink flow path may become unstable, and so the ejection velocity of the ink is reduced or made irregular. Accordingly, such an ink becomes liable to hold bubbles therein and hence has a possibility that the size of ink droplets may become varied, or the ejection direction of the ink may be disordered, resulting in deterioration of print quality.
When these bubbles stay in the ink for a long period of time, the bubbles are enlarged by gases or the like dissolved in the ink, which may cause the state of ejection failure of the ink in an considerable case.
In particular, an ink-jet recording method has recently been required to output an image of photograph-like image quality and hence to output a more bright or clearer color-image. Therefore, it has been required that the impact accuracy of an ink when conducting printing on a recording medium is improved, and that droplets of the ink ejected are made smaller. Therefore, it is necessary to more smooth the flow of the ink than before so as not to cause the retention of bubbles. As a measure for this, Japanese Patent Application Laid-Open No. 61-137750 has proposed a method for preventing the retention of bubbles, in which an ink-feeding member in an ink-jet recording apparatus is subjected to a lamination treatment with a compound having both hydrophilic group and hydrophobic group, thereby enhancing the wettability of the ink-feeding member with inks.
Japanese Patent Application Laid-Open No. 6-71885 has proposed a method for preventing the retention of bubbles, in which ions are implanted into a part of an ink-jet recording apparatus, with which an ink comes into contact, by ion implantation to conduct a hydrophilicity-imparting treatment, thereby enhancing the wettability of the ink-contacting member with inks. However, the above method comes to increase production cost, since a step of treating the ink-contacting part or member must be added upon the production of the ink-jet recording apparatus.
In the compound-laminating treatment proposed in Japanese Patent Application Laid-Open No. 61-137750, production cost is increased in that materials for making up the ink-jet recording apparatus must be increased. In addition, the method involves many problems such that the effect is observed only in the coated surface, and the material for the treatment must be selected in view of its adhesion property to a surface to be treated whenever a material for making up the ink-jet recording apparatus is changed.
Accordingly, it is an object of the present invention to provide an ink-contacting member by which the flow of an ink within an ink-jet recording apparatus can be simply smoothed without adding a new third component for an ink-jet recording head used only for the purpose of solving the above-described problems and naturally without adding a step attendant on the addition of the third component, thereby preventing printing failure and an ink breaking phenomenon due to the retention of bubbles to provide high-quality images stably.
Another object of the present invention is to provide an ink-absorbing member which permits achieving the stable recording of a high-quality image.
A further object of the present invention is to provide an ink tank which permits printing a high-quality image on a recording medium stably.
A still further object of the present invention is to provide an ink-jet cartridge useful in printing a high-quality image on a recording medium stably.
A yet still further object of the present invention is to provide an ink tank which can be used in recording excellent images stably.
A yet still further object of the present invention is to provide an ink-contacting member, an ink-absorbing member, an ink tank and an ink cartridge which permit achieving a further improvement of printing stability.
The present inventors have carried out an extensive investigation as to components of ink-jet printers with a view toward achieving the above objects. As a result, it has been found that when polyethylene, to which a phenolic antioxidant having an isocyanurate skeleton has been added, is used for an ink-contacting member, a substance having delicate wettability is eluted in an ink. The present invention has been led to completion on the basis of a quite new point of view that attention is paid to the component eluted out of the ink-contacting member for overcoming the above-described problems.
Namely, the above objects can be achieved by the present invention described below.
According to the present invention, there is thus provided an ink-contacting member used in an ink-jet recording apparatus, which comprises, as a principal component, a resin material obtained by adding a phenolic antioxidant having an isocyanurate skeleton represented by the formula 
According to the present invention, there is also provided an ink-absorbing member used in an ink-jet recording apparatus, which comprises, as a principal component, a resin material obtained by adding a phenolic antioxidant having an isocyanurate skeleton represented by the formula (I).
According to the present invention, there is further provided an ink tank used in an ink-jet recording apparatus, comprising an ink-absorbing member capable of holding an ink therein, and a casing housing the ink-absorbing member therein and having an opening part communicating with the air, wherein the ink-absorbing member comprises, as a principal component, a resin material obtained by adding a phenolic antioxidant having an isocyanurate skeleton represented by the formula (I).
According to the present invention, there is still further provided an ink-jet cartridge comprising an ink-absorbing member capable of holding an ink therein, an ink tank housing the ink-absorbing member therein, and an ink-jet recording head for ejecting the ink to be fed from the ink tank, wherein the ink-absorbing member comprises, as a principal component, a resin material obtained by adding a phenolic antioxidant having an isocyanurate skeleton represented by the formula (I).
According to the present invention, there is yet still further provided an ink tank capable of storing an ink to be fed to an ink-jet recording head, wherein at least a part of the ink tank, with which an ink comes into contact, comprises, as a principal component, a resin material obtained by adding a phenolic antioxidant having an isocyanurate skeleton represented by the formula (I).
Of the phenolic antioxidants having the isocyanurate skeleton represented by the formula (I), tris(4-tert-butyl-2,6-dimethyl-3-hydroxybenzyl)-isocyanurate may be preferred. The resin material may preferably be polyolefin, and the ink-contacting member may preferably be composed of an aggregate of polyolefin fibers. The polyolefin may preferably be polypropylene or polyethylene.